Spectrally sensitized silver halide photographic emulsion

ABSTRACT

Silver halide emulsions containing a supersensitizing combination of at least one sensitizing carbocyanine dye and at least one merocyanine dye containing a tetrazole nucleus giving a high white light sensitivity or red sensitivity.

United States Patent 1 Shiba et al.

[ Oct. 30, 1973 SPECTRALLY SENSITIZED SILVER HALIDE PHOTOGRAPHICEMULSION [30] Foreign Application Priority Data Sept. 28, 1970 Japan45/84532 [52] US. Cl. 96/126, 96/137, 96/140 [51] Int. Cl G03c 1/14,G03c 1/22 [58] Field of Search 96/124, 140, 126

[56] References Cited UNITED STATES PATENTS 2,430,558 11/1947 Carroll eta1 96/124 FOREIGN PATENTS OR APPLICATIONS 1,019,418 11/1957 Germany96/140 Primary Examiner-Norman G. Torchin Assistant Examiner-M. F.Kelley AtlomeySughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACTSilver halide emulsions containing a supersensitizing combination of atleast one sensitizing carbocyanine dye and at least one merocyanine dyecontaining a tetrazole nucleus giving a high white light sensitivity orred sensitivity.

17 Claims, 6 Drawing Figures PATENTEDum 30 I915 251G552; E5 Tzbzwdzi ONN0mm 9% O8 0% own o? 2% 8 8m cw Q8 0% com own own 8v 9 1- c an SPECTRALLYSENSITIZED SILVER HALIDE PHOTOGRAPHIC EMULSION BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to aspectrally sensitized silver halide photographic emulsion and moreparticularly to a silver halide photographic emulsion preparedby thecombined use of at least more than two kinds of sensitizing dyes toobtain a high white light sensitivity or red sensitivity.

The photographic sensitive materials are required to have highsensitivity at the specific wavelengths different from each otheraccording to the purpose for use.

2. Description of the Prior Art It has been well known in the art thatfor making such photographic sensitive materials certain kinds ofsensitizing dyes are added to a silver halide photographic emulsion toraise the sensitivity in the region of wavelengths longer thanthe regionof wavelengths of sensitivity intrinsic to saidsilver halide; that is,the art of spectral sensitization. Usually more than two kinds ofsensitizing dyes are used together, generally, for photographicsensitive materials having panchromatically sensitized spectralsensitivity in order to obtain a desired spectral sensitivitydistribution.

Many of the sensitizing dyes, however, bring about the lowering of thesensitivity of the emulsion in the intrinsic sensitivity region thereof,i.e., desensitization, while they bring about spectral sensitization.Therefore, it is quite advantageous to use at least two kinds ofsensitizing dyes, which are in a supersitizing relation to each otherand do not accompany desensitizing actron.

SUMMARY OF THE INVENTION The object of this invention is to lower thedesensitizing action and to raise both the sensitivity intrinsic tosilver halide and the panchromatically sensitized spectral sensitivityby using at least two kinds of sensitizing dyes.

The second object of this invention is to improve the image quality ofthe spectrally sensitized photographic sensitive material. Generally,the sensitizing dyes affect the development of the photographic emulsionand, in many cases, lower the quality of the photographic image.Especially, cationic dyes affect the infectious development, which isemployed for photographic plate making, and deteriorate the dot qualityobtained. Therefore, it is also the object of this invention to obtainhigh panchromatic sensitivity by supersensitization using a restrictedcyanine dye and another merocyanine dye, which have little effect oninfectious development, and to obtain good dot quality, which isdifircult to obtain by supersensitization using more than two kinds ofcyanine dyes together.

Merocyanine dyes are generally adsorbed Hat on silver halide to prohibitthe formation of the J aggregate of the carbocyanine dye and, as aresult thereof, lower the red sensitivity extremely. One of thecharacteristics of this invention is the discovery of a method forstrengthening the formation of the J aggregate of the restrictedcarbocyanine by strictly selecting the chemical structure of themerocyanine dye.

Other objects and advantages will become apparent from the followingdiscussion.

Theobject of ,this invention is accomplished by'the combined use of atleast one sensitizing carbocyanine dye having two heterocyclic nucleiselected from the group consisting of a benzothiazole nucleus,-abenzoselenazolenucleus, a fi-naphthoselenaz ole nucleus, and aB-naphthothiazole nucleus, the m'eso-position of said dye beingsubstituted with a methyl or ethyl group and, preferably, at least oneof the N-substituents of said heterocyclic nuclei being a sulfoalkylgroup or a carboxy alkyl groupvMore specifically, weare speaking ofsensitizing dyes of the following general formula (I), and at least onemerocyanine dye, wherein a tetrazole derivative nucleus and amerocyanine nucleus-are connected through a dimethine chain, morespecifically, sensitizing dyes of the following general formula (II):

wherein R and R each represents a lower alkyl group, such as methyl,ehtyl, propyl, gamma-sulfopropyl-, gamma-sulfobutyl, delta-sulfobutyl,beta-hydroxyethyl, beta-carboxyethyl, allyl group, etc.; A represents alower alkyl group, preferably a methyl or an ethyl group; Z and Z eachrepresents the 1 non-metallic atoms necessary to complete abenzothiazole; benzoselenazole, beta-naphthoselenazole, orbetanaphthothiazole nucleus, which may be substituted with a halogenatom, such as chlorine, bromine, etc., a lower alkyl group, such asmethyl, ethyl, etc., an alkoxy group, such as methoxy, ethoxy, etc., analko xycarbonylgroup, such .as methoxycarbonyl, ethoxycarbonyl, etc., anaryl group, such as phenyl, toluyl, etc.; X, represents an anion, suchas chloride, bromide,- iodide,

. methylsulfate, p-toluenesulfonate, etc.; m is 0 or 1, and

m 0 if an intermolecular salt is formed with R1 or R nucleus is definedas a heterocyclic nucleus'containing a O -ii-o= group (refer to C. E.Mees. The Theory of the Photographic Process," Revised Edition. pages4l5 to 420).

DETAILED DESCRIPTIONOF THE INVENTION The cyanine dyes of this inventionhaving the general formula (I) have their maximum sensitization partbetween 595 and 690 nm, and many of them have high red sensitivity. Someof the sensitizing dyes having the general formula (11) have theirmaximum sensitization part between 460 and 560 um, and others do notexhibit remarkable spectral sensitization action, even when usedtogether with a silver iodide emulsion.

The red sensitivity arising from the sensitizing dye of the generalformula (I) is further raised, thewhite light sensitivity is remarkablyraised and the silver halide photographic emulsion, which almost doesnot cause intrinsic desensitization, can be obtained by the combined useof at least one of the sensitizing dyes of the general formula (1) andat least one of the sensitizing dyes of the general formula (11), whichhave the said characteristics. Above all, the combination ofmeso-methyl-carbocyanine, being one of the sensitizing dyes representedby the general formula (I), and the sensitizing dye of the generalformula (ll) wherein Z is sulfur, remarkably raises the white lightsensitivity and red sensitivity, and brings about remarkable maximumsensitization around 630 nm. This shows that the dye having the generalformula (II) remarkably strengthens the J-band of the J-band type dye ofthe carbocyanine sensitizing dyes represented by the general formula(I). This is one of the unique characteristics of this invention. Thecombination of the dye represented by the general formula (I) (e.g.,mesoethyl-thiacarbocyanine) and the sensitizing dye represented by thegeneral formula (ll) wherein Z is an oxygen atom rather sensitizes whilestrengthening the J- band of the J-band type dye without changing thespectral sensitivity distribution thereof. This is effective for the redsensitization for the red-sensitive layer of color photography. Thetendency of the .l-band strenghtening, of the supersensitizing actionand of the effect of prohibiting the desensitization is not injured byusing oghochromatic sensitizing dyes, such as 2,2-cyanine,pseudocyanine, and the like. V

The sensitizing dyes of the general formula (1) do not deteriorate thedot quality obtained by the infectious development employed for thesensitive material for print plate making in proportion to the fact thatthey strongly and spectrally supersensitize to the relatively longwavelength of 690 nm. The application of the known supersensitizing artusing cyanine dyes together in order to raise the spectral sensitivitybadly deteriorates the dot quality. For example, the application of thesupersensitizing art described in the specification of US. Pats. Nos.2,533,426, 2,688,545, and 2,751,298, the specification of German Pat.No. 1,547,641, the specification of German Patent Prepublication No.1,813,001, Japanese Patent Publication No. 16169/68 and No. 4132/68 aredisadvantageous because of the reason described above.

The merocyanine dye represented by the general formula ratherstrengthens the infectious development, and is useful to obtain good dotquality. Accordingly, the supersensitizing art of this invention isuseful espe cially for the panchromatic sensitization of the sensitivematerial for printing plates which are to be subjected to the treatmentof infectious development.

The effects brought about by the groups R B and R the region of which isconcretely mentioned before, are

HzhOH CaH1 Those skilled in the art can readily synthesize thesensitizing carbocyanine dyes to be used in this invention according tothe description in the specification of U.S. Pat. Nos. 2,238,231,2,503,776 and 3,177,210, German Pat. Nos. 929,080 and 1,072,765, etc.,and the sensitizing merocyanine dyes according to the description in thespecification of German Pat. No. 1,019,418.

The spectral sensitization method of this invention is useful for thespectral sensitization of the gelatinosilver-halide photographicemulsion. It is also useful for the emulsion containing a hydrophilicpolymer, other than gelatin, such as agar collodion, water-solublecellulose derivatives, polyvinyl alcohol, polyvinyl- -pyrrolidonecopolymer and other synthesized hydrophilic resin, natural hydrophilicpolymer, gelatin derivatives, and the like.

The photographic emulsion to be used in this invention is suitably amixed silver halide comprising at least two of silver chloride, silverbromide and silver iodide. To produce the spectrally sensitizedphotographic emulsion in this invention, the sensitizing dye accordingto this invention is introduced into a photographic emulsion accordingto a conventional method. Usually, dyes are dissolved in a solvent, suchas methanol, ethanol, water, cellosolve, water-soluble ketones, etc.,and added to an emulsion. Alternatively, dyes may also be dissolved inan oil, slightly soluble in water, then added to water or a hydrophiliccolloid to disperse the same.

The mol ratio of the sensitizing carbocyanine to the sensitizingmerocyanine to be contained in the emulsion can vary widely from 9:1 to1:9 depending upon the effects desired. The amount of each of the dyesis preferably in the range of from 1 X 10" to l X 10 mol per mol ofsilver according to the character of the emulsion employed.

The photographic emulsion of this invention can be subjected to furtherhypersensitization and other supersensitization in the known manner. Inthe production, conventional additives, such as chemical sensitizers,

7 stabilizers, antibronzing agents, hardeners, surface active agents,antifoggants, plasticizers, development accelerators, color couplers,fluorescent brightening agents, may be contained in the photographicemulsion of this invention in a conventional manner.

The photographic emulsion of this invention may be coated in a commonmanner on a suitable support, such as a glass plate, film of a cellulosederivative, film of a synthetic resin, Baryta paper, resin-coated paper,etc.

A better understanding of the present invention will be attained fromthe following examples, which are merely intended to be illustrative andnot limitative thereof.

Examples A silver halide photographic emulsion was prepared 'by addingseparately the dye of this invention illustrated before and to be usedin this invention independently to a silver bromoiodide emulsion(AglzAgBr 7 molsz93 mols). On the other hand, a silver halidephotographic emulsion containing both the earbocyanine dye and themerocyanine dye was prepared.

7 pfthese emulsions was coated on a triacetylcel- TABLE 1 TheComposition of the Developer Metol 2 g Sodium sulfite 100 g Hydroquinone5 g Borax 2 g Water to make up 1 I.

In the following Table 2, the resulting white light sensitivity and redsensitivity obtained by the independent addition of the sensitizing dyesillustrated before and/or the combinedaddition thereof and the intrinsicsensitivity relative to that of the starting emulsion are given.

Table 2 Exper- Exsensitizing dye- Emul- I-Iaximum Rel- Rel- In-Specimenam-- Amount of dye s ion sansiative atlvc trintrotal ple addedtizawhite red sic gram No. No. ("5mo1/kg of tion lightsensisensiemulsion) (mm) sensitivity tivity tivity A (2) AgBr 600 90 94i /I 1 A (4) 630 100 90 90 Fig.1 A (8) E 632 130 120 Curve 1 (2) 5 0 82o 100 1 5 0 88 o 116 Curve 51 (8) 5 0 102 120 A (4) 1 (4) 632 A 140 120120 1 A (8) 1 (4) 632 170 146 120 Curve 2 2 A (4) 1 (4) 630 164 120 1164 9 (8) 42 86 o 100 4 A (4) X 9 (4) 632 120 100- 100 A (8) I 9 (4) 632150 120 100 7 (2) 540 o 110 5 7 (8) 540 o 116 5 A (4) '1 (4) 610/630 120100' A 7 (8) 610 150 100 116 5 8 (4) 530 76 o 88 i 8 (8) 530 76 o 88 L(2) g 600 70 25 94 6 L g 630 90 6o. 88 1, (8) 5 630 90 8o 6 L (4) 8 (4)628 100 68 88 L (8) g 8 (4) 628 12g 100 80 T3l :?ll'lq,- Expcr-Exsensitizing dye- Emuli-Iaximum Re l- Rel- In- Spec imenam- Amount ofdye sion sensia'tive ative trintrocal ple added tizawhite red sic gramNo. No. (lO" m0l/kg of tion light sensisensiemulsion) (nm) sensitivi bytivity tivity B g r 95 5 B (4) 6 11 135 88 Fig.6 7 B (8) 665 130 170 78Curve 6 (4) 535 100 0 110 Curve 9 545 1 1 O 9 J (2) 600 30 Fig.4 J (4)630 100 88 100 8 J (8) 630 128 98 J (4) 6 630 135 108 110 'f 8 J 6 (8)612 140 100 110 c (4) 3; 654 100 100 95 Fig.2

0 (6) 658 108 92 Curve 3 c (8) 660 110 90 2 85 O 116 Cfirve 2 9 c (6) 2H l 660 135 98 c (6) 2 (8) 660 152 1 6 100 Curve 4 3 (4) 1 5 8O 0 94 3(8) 1 520 88 0 90 lo 10 c (6) 3 (4) 660 118 130 94 c (6) 3 (8) j 660 11894 0 (1) 634 60 30 94 Fig.5 n G 4 7 43 9 G (4) 5 1 66 5 n 0 (2) 3 (4)655 82 60 90 G 3 55 82 73 9 Table II Cntinued Expcr- Exsensitizing dye-Emul- Maximum Rel- Rel- In- Specimenam- Amount of dye sion sensiativeative trin- "urotal ple acldad tization white red sic gram No. No.(lO'Smol/kg of (nm) light sensisensiemulsion) sensibivity civity bivity11 (6) 660 105 150 85 11 (8) 660 112 160 80v 4 00 100 Fig.5

l4 4 (8) 500 83 104 Curve 12 14 F (4) 4 (4) 642 11 88 94 F (4) 4 (8) 642110 83 104 G (2) 4 (4) 22 80 54 9O Curve 14 15 15 c 2) 4 a) 655 1 9 16 K(4) 6 (4) 630 100 100 Fig- 3 x (8) 6 (4) 630 1 8 110 100 Curve 7 a (1) 2(8) 684 94 210 104 Curve 8 Table H-Cntinued rtlxper Exsensitizing; dye-Eqmli-laxin aum Re1- TRe-L- In:- Spec- 1menarn- Amount of dye slonsens1- atlve. ative trlnirecal ple added tiza'bion white red sic gramNo. No. (lOinol/kg of 1 (nm) light ser'1siscnsiemulsion) sensitivi bytivity tivity 1 (4) u 650 120 86 19 I (6) 650 135 82 I I 5 5 14 75 4 1 1(4) 5 9 V 5 I (6) 1 (8) 650 110 178 104 E 5 9 71 92 E (4) 650 96 88 882O 1: (8) 650 10 85 E (4) 5 (4) 5 1 94 94 20 E (8) 5 (4) 650 110 9810(4) 540 85 0 106 21 10(8) 5 0 96 0 110 L (4) (4) 628 72 96 21 L (8)10(4) 628 138 108 9 22 22 L (4) 10(4)) 628 1 6 108 96 A (6 Q) 1 (4) 632'152 152 108 23 0(0. 3) 24 24 A (6 4) 1 (4i) 630 178 5 152 102 0(0. 3;)11(21) I H (1)) 670 108 260 86 5 1 Y I (4) H (1%) 680 100 164 84 26 A(4) A (4-). H (1)) 680 118 200 82 27 1s (4) In the aforementioned table,the white light sensitivity and the red sensitivity are given relativeto the corresponding sensitivities obtained by exposing to the saiddaylight source without a filter or through a red filter using a samplecontaining 4 X moi/kg of emulsion of the sensitizing dye C, beingcalculated as 100. The intrinsic sensitivity is given relative to thesensitivity obtained by exposing the starting emulsion through a bluefilter, being calculated as 100.

As is obvious from the result given in Table 2, the white lightsensitivity and the red light sensitivity obtained by the combined useof the sensitizing dyes of this invention are far higher than thoseobtained by the independent use thereof.

As is shown in Examples Nos. 2, 3 and 22 in Table 2, the sensitizingeffect obtained by the combination of at least one of the carbocyaninedyes and at least one of the merocyanine dyes is not deteriorated if anorthochromatic sensitizing dye already known, such as that of 11 or 12,is further used together. The orthochromatic sensitizing dyes usedtogether with the sensitizing dyes employed in this invention are, forexample, 2,2- cyanine and pseudo-type cyanine (e.g., 2'-thiacyanine)having the following chemical structures, but are not solely limited tothese.

(EzHs Although the present invention has been adequately discussed abovein the foregoing specification and examples, it is readily apparent thatvarious changes and modifications can be made without departing from thespirit and scope thereof.

What is claimed is:

l. A silver halide photographic emulsion comprising a supersensitizingcombination of at least one sensitizing carbocyanine dye having twoheterocyclic nuclei selected from the group consisting of abenzothiazole nucleus, a benzoselenazole nucleus, a B-naphthoselenazolenucleus and a B-naphthothiazole nucleus, the meso-position of said dyebeing substituted with a member selected from the group consisting of amethyl and an ethyl group, and at least one merocyanine dye in which atetrazole derivative nucleus and a merocyanine nucleus are connectedthrough a dimethine chain.

2. The silver halide photographic emulsion of claim 1, wherein at leastone of the N-substituents of the heterocyclic nuclei of the carbocyaninedye is a member selected from the group consisting of a sulfoalkyl and acarboxyalkyl group.

3. The silver halide photographic emulsion of claim 1, wherein thecarbocyanine dye is represented by the following formula (I) and themerocyanine dye by the following generalforrnula (II):

wherein R, and R, each represents a lower alkyl group; A represents amember selected from the group con sisting of a methyl and an ethylgroup; Z and Z,

represent nonmetallic atoms necessary to complete a.

ring selected from the group consisting of a benzothiazole nucleus, abenzoselenazole nucleus, a fi-naphthoselenazole nucleus, and aB-naphthothiazole nucleus; X

represents an anion; and m represents 0 or 1, provided that m 0 when anintermolecular salt is-formed:

wherein R and R each represents a lower alkyl group; B represents amember selected from the group consisting of a lower alkyl and an arylgroup; Z represents a member selected from the group consisting of =NRan oxygen atom, and a sulfur atom; R being a lower alkyl group.

4. The silver halide photographic emulsion of claim 3, wherein Z; of theformula (II) is an oxygen atom.

5. The silver halide photographic emulsion of claim 4, wherein Z, and Zof formula (I) are nonmetallic atoms necessary to complete a memberselected from the group consisting of a benzothiazole and aB-naphthothiazole nucleus.

6. The silver halide photographic emulsion of claim 3, wherein A'offormula (I) is a'methyl group and Z of formula (II) is a sulfur atom.

7. The silver halide photographic emulsion of claim 1, wherein theemulsion further contains at least one orthochromatic sensitizing dye.

8. The silver halide photographic. emulsion of claim 7, wherein theorthochromatic sensitizing dye is selected from the group consisting ofa 2,2'-cyanine dye and a pseudo-type cyanine dye.

9. The silver halide photographic emulsion of claim v1, wherein thecarbocyanine dye is selected from the group consisting of and themerocyanine dye is selected from the group 6 consi t ing of H I V{102E933 21 22 10. The silver halide photographic emulsion of claim and7, wherein the orthochromatic sensitizing dye is selected from the groupconsisting of N CHCHS :l S zHa O \N -S V7 7 C H;CH=CHI I 10 13. Thesilver halide photographic emulsion compris- 2H5 ing a supersensitizingcombination of and Se S a 2 s CH-,=CH fi CH N/ co COQCH3 N N rc miisoanmznm Da a and N-NCH:

l 1. A silver halide photographic emulsion comprising N CH 0 a supersensitizing combination of (iIH1C H=CH1 O S N s s MM WW M (13135 EH3 =CH=CH- 14. The silver halide photographic emulsion comprisg/ ing asupersensitizing combination of S S Z2115 S 02H =CH- :cn- J =CH- =CH C1C1 me CH N N If oHnasoaHN orrmsoa- (HmSOsH (HmsOr and and NN-CH, 1TNCH;CHI-CH s 40 CHCH o l L if I Hz-CH=CH 0 =5 zHs O Ig -S 2 11/ 2H5 HzCH--C2 s 15. The silver halide photographic material compris- 12. Thesilver halide photographic emulsion comprisin a l r ntai i th ilv r hlid l i f ing a supersensitizing combination of claim 1 V. V.V. mm 7 16.The silver halide photographic emulsion of claim 5 s 1, wherein the molratio of said carbocyanine dye to said merocyanine dye ranges from 9:1to l:9.' I 17. The silver halide photographic emulsion of claim 1,wherein each of said cyanine and merocyanine dye LL is present in anamount of l X l()' to I X l0 mol pcr nmsommcnma mol of Silven (HDaSOa'

2. The silver halide photographic emulsion of claim 1, wherein at leastone of the N-substituents of the heterocyclic nuclei of the carbocyaninedye is a member selected from the group consisting of a sulfoalkyl and acarboxyalkyl group.
 3. The silver halide photographic emulsion of claim1, wherein the carbocyanine dye is represented by the following formula(I) and the merocyanine dye by the following general formula (II): 4.The silver halide photographic emulsion of claim 3, wherein Z3 of theformula (II) is an oxygen atom.
 5. The silver halide photographicemulsion of claim 4, wherein Z1 and Z2 of formula (I) are nonmetallicatoms necessary to complete a member selected from the group consistingof a benzothiazole and a Beta -naphthothiazole nucleus.
 6. The silverhalide photographic emulsion of claim 3, wherein A of formula (I) is amethyl group and Z3 of formula (II) is a sulfur atom.
 7. The silverhalide photographic emulsion of claim 1, wherein the emulsion furthercontains at least one orthochromatic sensitizing dye.
 8. The silverhalide photographic emulsion of claim 7, wherein the orthochromaticsensitizing dye is selected from the group consisting of a 2,2''-cyaninedye and a pseudo-type cyanine dye.
 9. The silver halide photographicemulsion of claim 1, wherein the carbocyanine dye is selected from thegroup consisting of
 10. The silver halide photographic emulsion of clAim7, wherein the orthochromatic sensitizing dye is selected from the groupconsisting of
 11. A silver halide photographic emulsion comprising asupersensitizing combination of
 12. The silver halide photographicemulsion comprising a supersensitizing combination of
 13. The silverhalide photographic emulsion comprising a supersensitizing combinationof
 14. The silver halide photographic emulsion comprising asupersensitizing combination of
 15. The silver halide photographicmaterial comprising a layer containing the silver halide emulsion ofclaim
 1. 16. The silver halide photographic emulsion of claim 1, whereinthe mol ratio of said carbocyanine dye to said merocyanine dye rangesfrom 9:1 to 1:9.
 17. The silver halide photographic emulsion of claim 1,wherein each of said cyanine and merocyanine dye is present in an amountof 1 X 10 6 to 1 X 10 3 mol per mol of silver.